The figure that the HuffPo and other sources cite, that indoor marijuana cultivation accounts for 1% of electrical use in the U.S., is meaningless to me. I mean, how does that compare to other stuff? According to the report’s FAQ, that 1% figure works out to “22 billion kilowatt-hours/year estimated for indoor Cannabis.”

-PCs and printers: 23 kWh-Dishwashers: 29 kWh (I’ve read that electric dishwashers actually end up using fewer resources than washing dishes by hand, but I don’t have a source handy. I’m also not sure if those figure factor in the manufacture of dishwashers).-Color TVs and TV peripherals: 49 kWh-Refrigerators: 156 kWh (freezers add an additional 39 kWh)-Air conditioning: 183 kWh

That of course doesn’t include the carbon foot print of manufacturing the equipment. Nor the cost of producing TV shows, and the carbon foot print of data centers and servers to power the Internet. You and I are probably doing more environmental damage right now by writing and reading this blog post than my pot-smoking neighbors down the hall are.

That doesn’t mean that growing indoor weed couldn’t or shouldn’t be made more efficient. But “indoor marijuana cultivations uses slightly less than half the total amount of electricity spent powering TVs” is less impressive than saying “1% of U.S. power consumption in the U.S. goes to growing pot.”

Also of interest is the environmental footprint of other drugs. Marijuana has a much lower impact than crystal meth, because meth requires chemicals imported from India and China. Marijuana doesn’t generally have to travel far once it’s grown, which reduces its footprint.

The ecological case for decriminalizing drugs is probably stronger for drugs other than marijuana. From the report’s FAQ:

Does this study support the case for criminalization?
No. In fact, many argue that criminalization is an important driver towards energy-intensive indoor production. Criminalization also contributes to many of the energy inefficiencies in the process, including long driving distances, noise and odor suppression measures that undercut ventilation efficiencies, and off-grid power production that is far less efficient produces more greenhouse-gas emissions than many electric grids. Moreover, decades of criminalization has resulted in this energy-using sector being passed over by massive efforts to incentivize and mandate efficiency improvements. The analysis does suggest a role for improved management of energy use, in much the same way that we address the energy use and fuel economy of our cars, buildings, and appliances.

Does this study support the case for decriminalization?
Not really. People grow indoors for many reasons aside from criminalization, e.g., quality control, pest control, and year-round yield. Many producers with licenses choose to grow indoors. That said, in a scenario where production is legalized it is, in principal, easier to address the energy issues.

Update: I thought I should also mention that 22 kWh per year for growing pot is still a pretty high number, even when compared to TV and other stuff, in that only about 10% of the U.S. population smokes marijuana. However, I still don’t think it justifies alarmism.

5 Comments

I’m not quite sure why data from 2001 is making headlines in 2011, but that’s the mainstream press for you.

One thing that you didn’t mention at all was that lighting technology has drastically changed in the last decade. Even for high-end lights that you’ll find in grow rooms. Today, many growers have switched to LED lights which are much more energy efficient and don’t get nearly as hot as some of the more traditional sort of lights. Obviously this reduces overall energy use in a grow room because not only are the lights using less energy, but cooling systems can be turned down since the lights are no longer heating the room.

The marijuana growing data is more recent. The data I compared it to – television, dishwashers, etc. – is from 2001 because it was the only data I could find easily. There’s probably better data there.

LED lights should help thing substantially, but I’m told they’re still prohibitively expensive for many growers.

I should have read that more carefully, but you are right, LED lights are expensive, at least up front. I’d like to see how the costs compare after factoring in energy savings, reduced heat, and longer life.

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